libflash/file: add file abstraction for libflash

The functionality provided by libflash and libffs are useful and it would be
good to use them on dumps of flash or even access flash from userland through
MTD devices which are presented as files.

Signed-off-by: Cyril Bur <cyril.bur@au1.ibm.com>
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>

4 files changed, 238 insertions, 0 deletions

diff --git a/libflash/file_flash.c b/libflash/file_flash.c
new file mode 100644
index 0000000..d902672
--- /dev/null
+++ b/libflash/file_flash.c
@@ -0,0 +1,224 @@
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <string.h>
+
+#include <mtd/mtd-abi.h>
+
+#include "file_flash.h"
+
+/* The caller is going to have to supply this */
+struct file_flash_priv {
+	int fd;
+};
+
+/*
+ * Unfortunately not all file descriptors are created equal...
+ * Here we check to see if the file descriptor is to an MTD device, in which
+ * case we have to get the size of it differently.
+ */
+int file_setup(struct spi_flash_ctrl *ctrl, uint32_t *tsize)
+{
+	struct mtd_info_user mtd_info;
+	struct file_flash_priv *file_flash_data;
+	struct stat sbuf;
+
+	if (!ctrl || !ctrl->priv)
+		return -1;
+
+	file_flash_data = (struct file_flash_priv *)ctrl->priv;
+
+	if (fstat(file_flash_data->fd, &sbuf) == -1)
+		return -1;
+
+	if (S_ISCHR(sbuf.st_mode)) {
+		if (ioctl(file_flash_data->fd, MEMGETINFO, &mtd_info) == -1)
+			return -1;
+
+		ctrl->finfo->size = mtd_info.size;
+
+	} else if (S_ISREG(sbuf.st_mode)) {
+		ctrl->finfo->size = sbuf.st_size;
+
+	} else {
+		/* Not going to be able to work with anything else */
+		return -1;
+	}
+
+	if (tsize)
+		*tsize = ctrl->finfo->size;
+
+	return 0;
+}
+
+int file_set4b(struct spi_flash_ctrl *ctrl, bool enable)
+{
+	/* Always report success no matter what, this isn't relevent for files */
+	return 0;
+}
+
+int file_chipid(struct spi_flash_ctrl *ctrl, uint8_t *id_buf,
+		uint32_t *id_size)
+{
+	if (!ctrl || !ctrl->priv || !id_size || *id_size < 3)
+		return -1;
+
+	id_buf[0] = 'M';
+	id_buf[1] = 'T';
+	id_buf[2] = 'D';
+
+	*id_size = 3;
+	return 0;
+}
+
+int file_read(struct spi_flash_ctrl *ctrl, uint32_t addr, void *buf,
+		uint32_t size)
+{
+	int rc;
+	struct file_flash_priv *file_flash_data;
+
+	if (!ctrl || !ctrl->priv)
+		return -1;
+
+	file_flash_data = (struct file_flash_priv *)ctrl->priv;
+
+	rc = lseek(file_flash_data->fd, addr, SEEK_SET);
+	if ((off_t )rc == (off_t )-1)
+		return -1;
+
+	rc = read(file_flash_data->fd, buf, size);
+	if (rc == -1)
+		return -1;
+	/* TODO Perhaps deal with short reads */
+
+	return 0;
+}
+
+int file_write(struct spi_flash_ctrl *ctrl, uint32_t addr,
+		const void *buf, uint32_t size)
+{
+	size_t rc;
+	struct file_flash_priv *file_flash_data;
+
+	if (!ctrl || !ctrl->priv)
+		return -1;
+
+	file_flash_data = (struct file_flash_priv *)ctrl->priv;
+
+	rc = lseek(file_flash_data->fd, addr, SEEK_SET);
+	if ((off_t )rc == (off_t )-1)
+		return -1;
+
+	rc = write(file_flash_data->fd, buf, size);
+	if (rc != size)
+		return -1;
+	/* TODO Perhaps deal with short writes */
+
+	return 0;
+}
+
+int file_erase(struct spi_flash_ctrl *ctrl, uint32_t addr,
+		uint32_t size)
+{
+	struct stat sbuf;
+	struct file_flash_priv *file_flash_data;
+	uint32_t esize;
+
+	if (!ctrl || !ctrl->priv)
+		return -1;
+
+	/*
+	 * Input params addr = 0 and size = 0xffffffff mean libflash is telling us
+	 * to erase the entire thing.
+	 */
+	file_flash_data = (struct file_flash_priv *)ctrl->priv;
+
+	esize = (size == 0xffffffff && addr == 0) ? ctrl->finfo->size : size;
+	if (esize > ctrl->finfo->size)
+		return -1;
+
+	if (fstat(file_flash_data->fd, &sbuf) == -1)
+		return -1;
+
+	/*
+	 * If we're dealing with an MTD device then its possible that there is a
+	 * real flash device somewhere (as opposed to a regular file where the
+	 * assumption is that there is not).
+	 * In that case lets try to represerve that idea and use the erase ioctl.
+	 */
+	if (S_ISCHR(sbuf.st_mode)) {
+		struct erase_info_user erase_info = {
+			.start = addr,
+			.length = esize
+		};
+
+		if (ioctl(file_flash_data->fd, MEMERASE, erase_info) == -1)
+			return -1;
+
+	} else if (S_ISREG(sbuf.st_mode)) {
+		/* Regular file, erase is just write zeros */
+		char *section;
+
+		section = mmap(NULL, sbuf.st_size, PROT_READ | PROT_WRITE, MAP_SHARED, file_flash_data->fd, 0);
+		if (section == (void *)-1)
+			return -1;
+		bzero(section + addr, esize);
+		if (munmap(section, sbuf.st_size) == -1)
+			return -1;
+
+	} else {
+		return -1;
+	}
+
+	return 0;
+}
+
+/* To be called by tools wanting to use the libflash/libffs APIs */
+struct spi_flash_ctrl *build_flash_ctrl(int fd)
+{
+	struct spi_flash_ctrl *ctrl;
+	struct file_flash_priv *data;
+
+	ctrl = calloc(1, sizeof(struct spi_flash_ctrl));
+	if (!ctrl)
+		return NULL;
+
+	data = calloc(1, sizeof(struct file_flash_priv));
+	if (!data) {
+		free(ctrl);
+		return NULL;
+	}
+
+	data->fd = fd;
+
+	/*
+	 * Don't implement the low level interfaces because we aren't flash. This
+	 * will also force libflash to only call us with the high level interface.
+	 */
+	ctrl->cmd_rd = NULL;
+	ctrl->cmd_wr = NULL;
+
+	/*
+	 * Do implement everything else.
+	 */
+	ctrl->erase = &file_erase;
+	ctrl->write = &file_write;
+	ctrl->read = &file_read;
+	ctrl->chip_id = &file_chipid;
+	ctrl->set_4b = &file_set4b;
+	ctrl->setup = &file_setup;
+
+	ctrl->priv = data;
+
+	return ctrl;
+}
+
+void free_flash_ctrl(struct spi_flash_ctrl *flash_ctrl)
+{
+	free(flash_ctrl->priv);
+	free(flash_ctrl);
+}
diff --git a/libflash/file_flash.h b/libflash/file_flash.h
new file mode 100644
index 0000000..dc6b5d7
--- /dev/null
+++ b/libflash/file_flash.h
@@ -0,0 +1,11 @@
+#ifndef __FILE_FLASH_H
+#define __FILE_FLASH_H
+
+#include <libflash/libflash.h>
+#include <libflash/libflash-priv.h>
+
+struct spi_flash_ctrl *build_flash_ctrl(int fd);
+
+void free_flash_ctrl(struct spi_flash_ctrl *flash_ctrl);
+
+#endif /* __FILE_FLASH_H */
diff --git a/libflash/libflash-priv.h b/libflash/libflash-priv.h
index ba6da66..e59d829 100644
--- a/libflash/libflash-priv.h
+++ b/libflash/libflash-priv.h
@@ -223,6 +223,8 @@ struct spi_flash_ctrl {
 	 * been probed
 	 */
 	struct flash_info *finfo;
+
+	void *priv;
 };
 
 extern int fl_wren(struct spi_flash_ctrl *ct);
diff --git a/libflash/libflash.c b/libflash/libflash.c
index b5eaff5..a81ff4d 100644
--- a/libflash/libflash.c
+++ b/libflash/libflash.c
@@ -32,6 +32,7 @@ static const struct flash_info flash_info[] = {
 	{ 0x20ba20, 0x04000000, FL_ERASE_4K  | FL_ERASE_64K | FL_CAN_4B |
                                 FL_ERASE_BULK | FL_MICRON_BUGS,
                                                           "Micron N25Qx512Ax"   },
+	{ 0x4d5444, 0x02000000, FL_ERASE_ALL | FL_CAN_4B, "File Abstraction"},
 	{ 0x55aa55, 0x00100000, FL_ERASE_ALL | FL_CAN_4B, "TEST_FLASH" },
 	{ 0xaa55aa, 0x02000000, FL_ERASE_ALL | FL_CAN_4B, "EMULATED_FLASH"},
 };